May 31,1924 
The Heat of Wetting of Soil Colloids 
935 
Although the colloid content of a soil can not be deduced from the heat of 
wetting of the soil alone, a fair approximation of colloid content may be indi¬ 
cated by the formula, 
heat of wetting of soil 
heat of wetting of colloid 
This method is subject to some inaccuracy, due to failure to isolate a sample 
representative of the whole of the colloid, and due to alteration of the colloid 
through the process of extraction. These errors, however, may be in opposite 
directions and in certain cases compensating. On the whole, the heats of wetting 
of soil and colloid probably indicate the colloid content of a soil about as accu¬ 
rate^ as adsorption determinations. 
LITERATURE CITED 
(1) Anderson, M. S., Fry, W. H., Gile, P. L., Middleton, H. E., and Rob¬ 
inson, W. O. 
1922. ABSORPTION BY COLLOIDAL AND NON-COLLOIDAL SOIL CONSTITUENTS. 
U. S. Dept. Agr. Bui. 1122, 20 p. 
(2) Bouyoucos, G. J. 
1924. EFFECT OF IGNITION AT VARIOUS TEMPERATURES UPON CERTAIN 
physical properties of soils. Soil Sci. 171 135-139. 
(3) Fry, W. H. 
1923. THE MICROSCOPIC ESTIMATION OF COLLOIDS IN SOIL SEPARATES. 
Jour. Agr. Research 24: 879-883. 
(4) Gile, P. L., Middleton, W. H., Robinson, W. O., Fry, W. H., and Ander¬ 
son, M. S. 
1924. estimation of colloidal material in soils by adsorption. 
U. S. Dept. Agr. Bui. 1193, 42 p. 
(5) Linebarger, C. E. 
1901. ON THE HEAT EVOLVED WHEN LIQUIDS ARE BROUGHT IN CONTACT 
with powders. Phys. Rev. 13: 48-54. 
(6) Mitscherlich, E. A. 
1905. BODENKUNDE FUR LAND- UND FORSTWIRTE. 364 p., illus. Berlin. 
(7) - 
1913. BODENKUNDE FUR LAND- UND FORSTWIRTE. Ed. 2, 317 p., illus. 
Berlin. 
(8) Moore, C. J., Fry, W. H., and Middleton, H. E. 
1921. methods for determining the amount of colloidal material in 
soils, [preliminary paper.] Jour. Indus, and Engin. Chem. 
13: 527-530, illus. 
(9) Parks, G. J. 
1902. ON THE HEAT EVOLVED OR ABSORBED WHEN A LIQUID IS BROUGHT IN 
contact with a finely divided solid. Phil. Mag. and Jour. Sci. 
(VI) 4: 240-253. 
(10) Patrick, W. A., and Grimm, F. V. 
1921. heat of wetting of silica gel. Jour. Amer. Chem. Soc. 43: 
2144-2150, illus. 
(11) Patten, H. E. 
1909. heat transference in soils. U. S. Dept. Agr. Bur. Soils Bui. 
59, 54 p., illus. 
(12) Pouillet. 
1822. memoirs sur de nouveaux ph^nomIjnes de production de 
chaleur. Ann. Chem. et Phys. (II) 20: 141-162. 
(13) Robinson, W. O. 
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(14) Rodevald, H. 
1896. untersuchungen uber die quellung der starke. 87 p., illus. 
Kiel and Leipzig. 
(15) Stellwaag, A. 
1882. UNTERSUCHUNGEN UBER DIE TEMPERATURERHOHUNG VER- 
SCPIEIDENER BODENCONSTITUENTEN UND BODENARTEN bei con- 
* DENSATION von flussigem UND dampfformigem wasser, 
sowie von gasen. Forsch. Geb. Agr. Phys. 5: 210-227. 
96039—24f-7 
